Reddit reviews The Crusades: A History

Well, there's a good reason they didn't destroy Jerusalem or Mecca... They would need to get to Jerusalem or Mecca first. The Mongol Ilkhan Ghazan Khan may have controlled Jerusalem for, at most, four months in 1300 before retreating out of Syria entirely (there is much debate if they took the city or not), but by then the Ilkhanids were in the process of converting to Islam and probably wouldn't have wanted to destroy the city as a result.

Even when the Mongols first entered Palestine in 1260, the leading general Kitbuqa was a Nestorian Christian and the Mongols had begun making negotiations with the Crusaders over the status of Jerusalem. There was no interest in just destroying it. (Besides, it had just been destroyed in 1244 by a group of Khwarzemian mercenaries hired by the Ayyubids.)

The bigger answer to your question is that Jerusalem and Mecca and are not strategically important for the Mongols. Mecca is way out in the middle of nowhere. Controlling it would give a Muslim ruler some added prestige, but otherwise...

Jerusalem had also lost a lot of its strategic value thanks to the Crusades. The city walls were regularly torn down (to let anyone know if they take the city, it will be taken right back), for example.

When Jerusalem was in reach of the Mongols, something much more important would be happening in another part of the empire that would require attention. In 1260, Hulagu had to go to Mongolia to deal with the succession after the Great Khan Mongke died, taking enough of the army with him that the Mamluks were able to defeat them at Ayn Jalut.

When Ghazan and his general Mulay raided Palestine in 1300, it was following a surprise victory at Aleppo and they primarily chased the fleeing Mamluks back to Egypt. After a couple of months, they decided to retreat back across the Euphrates, probably because they needed better pastures for their horses.

As for the first part of your question, what is the religion of the Mongols? Well, that's a bit of a vague question. There were lots of different kinds of Mongols at different times. During the life of Genghis Khan, they were mostly Shamanistic. The Ilkhanate successor state (the Mongols who ruled Iran and Iraq) were Christian for a period of time and then converted to Islam. The Golden Horde (the Mongols who ruled Russia) were actually the first Mongols to convert to Islam. In the east, Mongols took on different forms of Buddhism. In a lot of ways the Mongols were fairly tolerant of different religions, maybe even curious about a variety of religions.

Don't have my sources for anything specific here in front of me, but any survey of Crusading and Mongol history should get you to them. I would recommend Riley-Smith's The Crusades and David Morgan's The Mongols.

A few titles on specific topics that seem uncovered:

• The Thirty Years War by C.W. Wedgwood -- Written in the '30s, this is still probably the best single volume on the topic (in English anyway). Fantastic place to start for anyone looking to get into a hugely significant though often overlooked conflict in European History. It was recently republished in paperback so shouldn't be too hard to come by.
  
  
• The Crusades: A History by Christopher Riley-Smith -- There are endless books on the various Crusades from an endless array of perspectives and focuses. To me, Riley-Smith is the best single volume on the whole subject. Again a great starting point for those new to the area.
  
  
• The Atlantic World: Europeans, Africans, Indians and Their Shared History, 1400-1900 by Thomas Benjamin -- This is a rather hefty work but serves as a wonderful encapsulation of the subject of Atlantic History. As is often the case in this field, particular attention is paid to the complex interconnections of economic and social exchange at various edges of the Atlantic World. For something a little more focused, The British Atlantic World, 1500-1800 by David Armitage is also great.
  
  
• Seven Myths of the Spanish Conquest by Matthew Restall is an awesome take on the subject. Restall basically debunks most modern misconceptions about the conquest of South America drawing on an array of creative source material. For primary reading on the conquest of Mexico specifically, by far the most important is The Conquest of New Spain by Bernal Diaz del Castillo-- basically reads as an adventure novel.

I was told by a historian that Jonathan Riley-Smith is one of the leading academics on the Crusades.

http://www.amazon.com/The-Crusades-History-Jonathan-Riley-Smith/dp/0300101287

Just as interesting and, from what I've been told, respected (to me, even more interesting, since the Arabs tend to be real drama-queens and the book seems to enforce that)

http://www.amazon.com/Crusades-Through-Arab-Eyes-Essentials/dp/0805208984